by Kevin Gallagher
This article is an excerpt from the postings on The 13th Fret discussion forum.
Here's the sequence that I've used for over 15 years and haven't had a piece fall out yet. You'll probably get as many methods as luthiers answering you post here, but this has worked for me so far.
After I've cut and dressed all of the pieces of my inlay to ensure that they fit together nicely, I'll glue them together like a puzzle to form one piece. I glue them together on a piece of material having the same radius as my fingerboard that they will be laid into. Flat if it's going into a headstock. Just lay apiece of waxpaper down under the inlay pieces to keep them from being glued to the surface underneath.
Many times, I'll lay the drawing or a copy of it under the wax paper and do all of the gluing over it to be sure that I'm maintaining my original layout's dimensions.
Once that's done, you can handle the entire project as one piece. peel the waxpaper off of the back and lay it onto the fingerboard it's going into. I don't glue it down during the tracing process, but yoiu may find that you'd like to use a soft glue such as DUCO or another acetone based cement to temporarily hold it in place while you scribe or cut around it.
I alwaya use a very small X-acto knife with a swiveling tip to trace around my inlay. This way there is actually a cut being made as an outline in stead of the line being simply pressed into the wood by a scribe point dragging around it. The cut line offers two benefits when proceeding, it gives a clean shear line as I rout the opening with my spiral down bit and also holds the color used to make it much more visible.
After I've traced the inlay with my X-acto blade, being sure that there is a continuous cut all the way around the piece as close to it as possible, I take contractor's line chalk (usually blue in my case) and sprinkle a little inside the cut line and rub it around over the line with my finger. The bright blue chalk is forced into the cut line and stays put nicely under the vibration and breeze caused by the Dremel tool running close to it. It gives a nice clear line to follow as I rout and it turns black when it makes contact with my fill glue. The white chalk stays light and if a fleck or two are left behind and may be visible in any small gaps as white or light gray spots.
After I've routed the hole and used a pick or scribe and X-acto blade to clear any corners that were too small for the radius of my spiral down bit, I try the inlay over it and clear it until I have a good fit that will need little or no filler.
I then drop the inlay into place and allow a small drop of thin Cyanoacrylate glue to ooze under at an edge to hold it in place while I fill being careful to not use too much so that it actually fills to the surface of the fingerboard.
With the inlay securely in its hole, I open a small box of Ebony dust that I keep on my bench for filling inlay. I've used epoxies and black fillers, but have had shrinkage and a plastic like appearance around the edges so I use CA glue and real Ebony dust. I save small offcut fingerboard ends and bridge stock scrap to grind on a sander and recover it for this purpose.
I sprinkle a liberal amount of the dark dust over the inlay and work it into the small gaps surrounding any of the pieces with my fingertip. I will leave a covering of the dust over the entire inlay and then drip thin CA glue onto the dust. The Ebony dust helps to keep the glue from running away from the inlay to the edges of the fingerboard and also allows a buildup of the glue/dust mixture to dry on top for leveling.
I never use accelerator to speed the drying process at this point, but allow the glue to air dry. The accelerator can cause the glue to heat up and bubbles to form in it that will appear after leveling. It can also cause the glue to expand under the inlay and lift it slighly causing it to be sanded thin or through when leveled later.
After everything is complately dry, I level the glue/dust and inlay all at the same time and restore the radius to the fingerboard surface. The entire board will be trued later before fretting.
At this point, any small gaps that may need attention will be clearly seen and can be filled with glue and dust if necessary and releveled after dry.
I always recut my slots after the entire process is complete. To do this, I use a Dremel with a .023' carbide dental bit to match my original fret slot dimension. I just plunge throught the inlay and the bit follows the portion of the slot that is open below it in the board.
Finally, I chamfer the edges of each slot that passes through the inlay with a Carbide pointed bit to allow the frets to be pressed in without chipping or lifting the inlay pieces.
Maybe a bit different than some the techniques used by others, but it has always worked nicely for me. I learned it from one of the best inlay artists in the business who still does a huge amount of hand cutting for some of the major builders as well as some small shops.
Regards and hope this all helps,